This invention relates to apparatus for shearing, chopping or shredding solid materials, and more particularly for converting stockpiled environmentally designated "waste" items of various sizes, shapes and substances into substantially uniformly reduced particle size products, for more efficient permanent disposal, commercial recycling, or other utilization. Waste items such as are particularly difficult to handle by such machines include for example scrap automobile and truck tires and scrap insulated electrical conductors and the like, because of the unique tumble/flow characteristics of the remnants of such items after they have been chopped or shredded. Typically, an apparatus for such purposes includes conveyor means for carrying the items to be processed from ground level to the gravity in-feed of a shredding mechanism; and a classifying device for passing to discharge products which have been reduced thereby to prescribed particle sizes.
It is know that grinding/shredding/chopping machines in systems of the type referred to may be most efficiently operated from the power, time and labor cost standpoints in such manner that the "first pass" of items through the machine need not all be at once reduced to the prescribed maximum sized product. This is because the effects of alternately peak and minimum or no power demand fluctuations invariably encountered in the feeding of such machines may be minimized by use of oversize remnant return elevators. Accordingly, oversize return elevators are usually employed and the shredding or chopping machines are set to initially pass some percentage of oversize remnants. However, the present invention provides for such systems an improved oversize remnant return elevator which more efficiently copes with the specific tumble and flow characteristics of masses of the chopped or shredded remnants of the above mentioned kinds of waste items, whereby the overall efficiency of operation of the system apparatus is markedly improved.